Despite coaching and front-office shortcomings, the Indianapolis Colts have remained competitive mostly because they have an elite quarterback. Andrew Luck is a major difference-maker, and his critics who say otherwise are fools.

Oddsmakers say this: Without Luck, the Colts would be underdogs to one of the NFL’s worst teams.

Luck, still rehabbing from offseason surgery on his right shoulder, admitted Saturday that he might not be ready for Indianapolis’ regular-season opener. At several Las Vegas books, the Colts are posted as 3-point road favorites over the Los Angeles Rams on Sept. 10.

Jimmy Vaccaro, oddsmaker at the South Point sports book, took the game and the Colts’ season win total off the board amid the mystery surrounding Luck’s status.

“We have been careful with the Colts the whole time,” Vaccaro said. “I think it’s a major change without Luck. I think this thing is much worse than they are saying.”

The Colts are not saying much about Luck’s progress, and he would not even say if he’s throwing a football yet. He did say he’s throwing a tennis ball. As the team opened training camp, he would not commit to a timetable on his return to the practice field.

Vaccaro speculated Luck could miss the first month of the season and maybe more, so he took down Indianapolis’ win total, which was 8½ (under minus-115).

The Colts finished last season 8-8, third in the AFC South, and missed the playoffs. Luck finished with 31 touchdown passes and 13 interceptions. He was sacked 41 times, the second-highest total in the league.

A key factor in determining a quarterback’s value to the point spread is the quality of the backup. Behind Luck on the depth chart is Scott Tolzien, an undrafted free agent in 2011. Tolzien rates as an average backup. When a concussion sidelined Luck for a week in November, Tolzien started and passed for 205 yards and one touchdown with two interceptions in a 28-7 loss to Pittsburgh.

“I disagree with him,” Vaccaro said. “Luck is in the top 10, not top five.”

Andrews said the difference in Indianapolis from Luck to Tolzien is seven points, meaning the Colts could be 4-point underdogs at L.A. in Week 1 if Tolzien is the starter. Vaccaro said he would probably make the Rams 2-point favorites with Luck out.

The Rams were an offensive mess last season, finishing 4-12, including 0-7 with rookie Jared Goff as their starting quarterback. Goff passed for five touchdowns with seven interceptions as a starter. Three of his touchdown throws came in a 49-21 loss at New Orleans. Goff was not good, to say the least.

Still, Goff would go off as a favorite in the opener if Tolzien is the Colts’ quarterback.

“Only because it’s the first game of the season, I give the Rams a little more credit,” Vaccaro said. “It’s not the middle of the season when they are 2-8.”